I have noticed that, right after implementing the ability to store moons, in the Planets table all planets (except one) are marked as deleted, hence it does not seem to be restricted to a single player.
The incident occurred at 16:09:48 local time, as all planets have that time as deletion time.
I have found the following in the access log of my server:
127.0.0.1 - - [12/Jan/2016:16:09:48 +0100] "POST /OGNext-0.3-SNAPSHOT/api/userscript/moons HTTP/1.1" 200 38
127.0.0.1 - - [12/Jan/2016:16:09:48 +0100] "POST /OGNext-0.3-SNAPSHOT/api/userscript/planets HTTP/1.1" 200 38
It is definitely related to the /moons or /planets endpoint, but I'm unsure which one exactly or what exactly is going on.